Abu Nu’aym reported: Ibrahim ibn Adham, may Allah have mercy on him, said, “Verily, whoever knows himself will be busy with himself. Whoever knows his Lord will be busy with his Lord to the exclusion of anything else.”
Source: Ḥilyat al-Awliyā’ 8/15
عن أبي نعيم قال إِبْرَاهِيم بْن أَدْهَم رحمه الله إِنَّهُ مَنْ عَرَفَ نَفْسَهُ اشْتَغَلَ بِنَفْسِهِ وَمَنْ عَرَفَ رَبَّهُ اشْتَغَلَ بِرَبِّهِ عَنْ غَيْرِهِ
8/15 حلية الأولياء وطبقات الأصفياء